ABSTRACT (RECRUITMENT AND RETENTION CORE) The Recruitment and Retention Core (RRC) will serve as the engine propelling successful formulation and operation of our DISCOVERY (Determinants of Incident Stroke Cognitive Outcomes and Vascular Effects on RecoverY) Network. Post-stroke cognitive impairment and dementia (PSCID) affects over 30-40%, leading to devastating disability and death. Currently, a major obstacle in the field is the lack of statistically robust studies based on patients admitted to the hospital with acute stroke, including acute ischemic stroke, intracerebral hemorrhage, aneurysmal subarachnoid hemorrhage, and recruited to participate in systematic assessment of early and late mechanisms of PSCID. To overcome this challenge, a large-scale scientific effort is required, driven by a unifying hypothesis and an overarching goal to identify and characterize stroke subtypes that increase PSCID risk and the additional clinical factors and comorbidities that contribute to or protect diverse US populations from this devastating disability. We propose a new NINDS-funded DISCOVERY Network: a large, multi-center national network of excellence designed to address the gap in knowledge of the clinical predictors and biological causes of PSCID. The engine of recruitment and retention behind this project is the proposed RRC led by a clinical trialist with proven record of success of executing multi-site, large-scale hospital-based studies with robust stroke subtype phenotyping and post-stroke outcome assessment model. We will employ highly developed recruitment and retention (R&R) techniques typically reserved for phase III multicenter randomized trials to assemble large numbers of well-characterized cohorts of stroke patients. We have assembled a team of experts in cerebrovascular clinical trials with established records of hospital-based enrollment of acute stroke patients, as well as experts in enhancing recruitment of health disparities populations within trials. Utilizing the vast multi-site stroke study R&R experience, RCC Core leadership, working closely with StrokeNET and other NINDS-funded initiatives, will adapt successful and validated CREST-2 processes for site selection and patient recruitment and retention. Further, we will develop a novel and efficient centralized phone- based outcomes assessment hub and training modules for clinical site personnel, assuring high-quality control and high-efficiency acquisition and transfer of clinical data, imaging and biospecimens to the DISCOVERY Repository. The DISCOVERY RRC will establish a valuable resource for the wider scientific community, and this new knowledge will be used to develop novel therapies to prevent cognitive impairment and promote cognitive recovery following stroke.